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Paper II — 2022 May (Supplementary) (2010 Scheme) — Q1

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Paper II
2022 May (Supplementary) (2010 Scheme)

Question

Classify Thyroid inhibitor drugs. Describe the mechanism of action, and adverse effects of carbimazole. Explain the role of iodides in hyperthyroidism. (2+2+2)

Q16 marksEssays

Answer

Classification of thyroid inhibitor (antithyroid) drugs

GroupExamples
ThioamidesMethimazole (Carbimazole is its prodrug), Propylthiouracil (PTU)
Iodide compoundsLugol’s iodine, Potassium iodide (high-dose)
Radioactive iodineI-131
Beta-blockers (symptomatic adjunct)Propranolol

Carbimazole — mechanism and adverse effects Mechanism: carbimazole → converted to methimazole → inhibits thyroid peroxidase → blocks iodide oxidation, organification, and coupling of iodotyrosines → new hormone synthesis is blocked (existing stored hormone still releases, so clinical effect takes weeks to appear).

Adverse effects: agranulocytosis (the most feared, idiosyncratic — patients counselled to report fever/sore throat immediately), rash, hepatotoxicity, teratogenicity (aplasia cutis — avoided in the first trimester of pregnancy).

Role of iodides in hyperthyroidism High-dose iodide paradoxically inhibits thyroid hormone release and synthesis — the Wolff-Chaikoff effect — a rapid-onset (hours to days) but transient autoregulatory suppression (the thyroid “escapes” within 1–2 weeks). This rapid-but-transient property makes it useful specifically for short-term pre-operative preparation (reducing thyroid vascularity/friability before thyroidectomy) and for acute thyroid storm management, never as sole long-term therapy.

  1. 1Thyroid Hormones and Antithyroid Drugs

Other Years Asked

  1. 1T4 and very low TSH levels. A diagnosis of hyperthyroidism was made. (2022 July (Supplementary) (2019 Scheme)Essay · 10 marks
  2. 2Compare Radioactive Iodine and Carbimazole.2024 March (Supplementary) (2019 Scheme)Short Essay · 8 marks
  3. 3(2023 July (Supplementary) (2019 Scheme)Essay · 6 marks
  4. 4A 32years old woman, presented with complaints of weight loss, palpitations, sweating, irregular menses and occasional tremors of hands since 2-3 months. Clinical examination revealed a diffusely enlarged thyroid gland and blood tests showed decreased TSH. She was started on medication for Grave’s disease.2025 March (Supplementary) (2010 Scheme)Essay · 6 marks
  5. 5Classify antithyroid drugs. Write the advantages and disadvantages of using radioactive Iodine. (2+2+2)2021 February (Supplementary) (2010 Scheme)Essay · 6 marks
  6. 6A 35 years old woman came with complaints of heat intolerance, retraction of upper eyelid and menstrual irregularities. Her T3 , T4 , FT4 & FT3 are elevated while TSH is suppressed. Answer the following:2015 February (2010 Scheme)Essay · 6 marks
  7. 7Treatment of thyrotoxic crisis.2023 January (Supplementary) (2019 Scheme)Short Answer · 4 marks
  8. 8Pharmacotherapy of Thyrotoxic crisis (thyroid storm)2024 June (Supplementary) (2019 Scheme)Short Answer · 4 marks
  9. 9Mechanism of action, uses and adverse effects of Radio active iodine.2025 March (Supplementary (SAY)) (2019 Scheme)Short Answer · 4 marks
  10. 10Carbimazole2022 October (Supplementary) (2010 Scheme)Short Note · 3 marks
  11. 11Radioactive Iodine2024 March (Supplementary) (2010 Scheme)Short Note · 3 marks
  12. 12Anti thyroid drugs2014 September (Supplementary) (2010 Scheme)Short Note · 3 marks
  13. 13Radioactive Iodine2021 May (Supplementary) (2010 Scheme)Short Note · 3 marks
  14. 14Lugol’s Iodine is given for 10 days prior to thyroidectomy surgery for Grave’s disease.2023 July (Supplementary) (2010 Scheme)Short Answer · 1 mark
  15. 15Anti-thyroid drugs2018 July (Supplementary) (2010 Scheme)Short Answer · 1 mark
  16. 16Explain the use of propranolol in thyrotoxicosis.2018 February (2010 Scheme)Short Answer · 1 mark
  17. 17Methimazole acts by:2024 December (Supplementary) (2019 Scheme)MCQ · 1 mark
  18. 18Antithyroid drugs2013 April (2010 Scheme)Short Answer · 1 mark
  19. 19Drug used in thyrotoxic crisis2014 March (2010 Scheme)Short Answer · 1 mark
  20. 20Propylthiouracil2025 August (Supplementary) (2010 Scheme)Short Answer · 1 mark
  21. 21Anti- thyroid drugs safe during pregnancy2017 August (Supplementary) (2010 Scheme)Short Answer · 1 mark
  22. 22Thyrotoxic crisis.2015 September (Supplementary) (2010 Scheme)Short Answer · 1 mark
  23. 23Anti thyroid drugs2016 October (Supplementary) (2010 Scheme)Short Answer · 1 mark
  24. 24Radioactive iodine2020 February (Supplementary) (2010 Scheme)Short Answer · 1 mark
  25. 25Use of Propranolol in Thyrotoxic crisis.2024 March (Supplementary) (2010 Scheme)Short Answer · 1 mark
  26. 26The preferred drug for her is:2024 December (Supplementary) (2019 Scheme)MCQ · 1 mark
  27. 27 Carbimazole for treatment of Thyroid storm2024 August (Supplementary) (2010 Scheme)Short Answer · 0.3 marks
  28. 28Antithyroid drugs2019 February (2010 Scheme)Short Answer · 0.3 marks

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